The coupling between coordinated propiononitriles in <i>trans</i>-[PtCl<i><sub>n</sub></i>(EtCN)<sub>2</sub>] (<i>n</i> = 2, 4) and the 1,2-hydroxylaminooximes
HON(H)CMe<sub>2</sub>C(R)NOH (R = Ph <b>1</b>, Me <b>2</b>) proceeds smoothly in CHCl<sub>3</sub> at ca. 40−45 °C and gives <i>trans</i>-[PtCl<i><sub>n</sub></i>{NHC(Et)ON(H)CMe<sub>2</sub>C(R)NOH}<sub>2</sub>] (<i>n</i> = 2, R = Ph <b>5</b>, Me <b>6</b>; <i>n</i> = 4, R = Ph <b>7</b>, Me <b>8</b>) in 80−85% isolated
yields. The reaction is highly regioselective, and both spectroscopic (IR; FAB<sup>+</sup>-MS; 1D <sup>1</sup>H, <sup>13</sup>C{<sup>1</sup>H}, and <sup>195</sup>Pt
NMR; and 2D <sup>1</sup>H,<sup>13</sup>C HMQC, <sup>1</sup>H,<sup>13</sup>C HMBC, and <sup>1</sup>H,<sup>15</sup>N HMQC NMR) and X-ray data for <b>6</b><b>−</b><b>8</b> suggest that the
addition proceeds exclusively via the hydroxylamine moiety of the 1,2-hydroxylaminooxime species; the existence
of an oxime group remote from the nucleophile was also confirmed. Heating of <b>6</b> in air leads to its conversion to
the unusual nitrosoalkane complex [PtCl<sub>2</sub>{HO<u>N</u>C(Me)C(Me)<sub>2</sub><u>N</u>O}] (<b>9</b>), whereas in the case of <b>5</b>, only the metal-free salt [H<sub>3</sub>NC(Me)<sub>2</sub>C(Ph)NOH]<sub>2</sub>(NO<sub>3</sub>)Cl·H<sub>2</sub>O (<b>10</b>) was isolated. To compare the kinetic aspects and trends in
the addition of both types of nucleophiles (oximes and hydroxylamines; for the latter, see our recent work: <i>Inorg.
Chem</i>. <b>2005</b>, <i>44</i>, 2944) to coordinated nitriles, a kinetic study of the addition of HONC(CH<sub>2</sub>Ph)<sub>2</sub> to [Ph<sub>3</sub>PCH<sub>2</sub>Ph][PtCl<sub>5</sub>(EtCN)] (<b>11</b>) to give [Ph<sub>3</sub>PCH<sub>2</sub>Ph][PtCl<sub>5</sub>{NHC(Et)ONC(CH<sub>2</sub>Ph)<sub>2</sub>}] (<b>12</b>) was performed. The calculated
rate constant <i>k</i><sub>2</sub> of 3.9 × 10<sup>-6</sup> M<sup>-1</sup> s<sup>-1</sup> at −20 °C for the addition of the oxime indicates that the hydroxylamine
is, by a factor 1.7 × 10<sup>4</sup>, more reactive toward the addition to nitriles than the oxime. Results of the synthetic,
kinetic, and theoretical (at the B3LYP level of theory) studies have demonstrated that the high regioselectivity of
the reactions of the 1,2-hydroxylaminooximes with ligated nitriles is both kinetically and thermodynamically controlled.